Spanning members for bridging purposes

ABSTRACT

This invention relates to semi-rigid inflatable spanning members which are used for bridging purposes particularly for laying down temporary bridges over gaps in open terrain, or over a watercourse. In the prior art these spanning members are constituted by a plurality of inflatable members housed within an envelope above which are arranged rigid plates: these plates are connected together end to end so as to form an arched bearing surface. In accordance with the invention, the envelope is bordered by a cable which engages laterally in channels provided at either side of the rigid plates and this cable is held in place by a suitable locking means.

United States Patent [1 1 Delamare [451 July 15,1975

1 1 SPANNING MEMBERS FOR BRIDGING PURPOSES [75} Inventor: Guy Robert Delamare, Herblay,

France [73] Assignee: Societe Superflexit, Courbevoie,

France 221 Filed: May 1,1974

2: Appl. No.: 466,005

3,134,116 5/1964 Adkins 14/1 3,258,800 7/ 1 966 Robinsky 3,685,074 8/1972 Marshall 3,824,644 7/1974 Stranzinger 14/27 Primary Examiner-Nile C. Byers, Jr. Attorney, Agent, or Firm-Fitzpatrick, Celia, Harper & Scinto [57] ABSTRACT This invention relates to semi-rigid inflatable spanning members which are used for bridging purposes particularly for laying down temporary bridges over gaps in open terrain, or over a watercourse. 1n the prior art these spanning members are constituted by a plurality of inflatable members housed within an envelope above which are arranged rigid plates: these plates are connected together end to end so as to form an arched bearing surface. in accordance with the invention, the envelope is bordered by a cable which engages laterally in channels provided at either side of the rigid plates and this cable is held in place by a suitable locking means.

8 Claims, 8 Drawing Figures 1 SPANNING MEMBERS FOR BRIDGING PURPOSES The present invention relates to spanning members for bridging purposes, such members being semi-rigid and inflatable.

To allow vehicles to pass over a gap or an opening in terrain, or over a watercourse, it may be necessary to use a rigid girder the strength of which needs to be high, particularly under bending stresses. However, the weight of such a rigid girder is very great, even when it is made in sections capable of being dismantled.

To overcome these drawbacks, it has been proposed to use an inflatable spanning member which can easily be collapsed, and which is very light, thus making it easy to transport and install using light-weight lifting and handling means. It is possible to break down such a spanning member into light-weight parts which can easily be set up and dismantled. In addition, such a spanning member is able to support heavy loads despite its own low weight. More particularly, the invention relates to semi-rigid inflatable spanning members constituted by a plurality of inflatable members arranged within an envelope, above which are arranged rigid plates which are connected together end to end and which form an arched bearing surface. Hereinafter such a spanning member will be referred to as of the kind described.

In a spanning member of the kind described the invention consists in that said envelope is bordered by a cable which engages laterally in channels provided on either side of said rigid plates, the said cable being held in place in the said channel by a locking member.

The rigid plates form a backbone for the composite spanning member of which they constitute the upper, compressed chord. Due to their rigidity under flexure they distribute the high pressure exerted by e.g. the tires of a vehicle over a sufficiently large area to encounter support reaction from the cushion, which is inflated to a low pressure. The lower part of the envelope forms the tensioned chord of the composite spanning member, while the limited-expansion chambers confined between the bearing surface and the envelope, one pressurised, separate the two members so as to contain shear forces, and to hold the assembly in shape and provide cohesion between the various components.

The semi-rigid spanning members may be used in any application where it is necessary for a localised load to be supported or allowed to pass by a member which is easily transportable and can quickly be set up and which rests wholly or partly on the ground, or possibly on water. It may thus form either a bridge proper to allow a vehicle to pass over a gap or an opening, in terrain, or it may form a causeway which rests on ground which is too uneven or flssured or insufficiently strong to allow a vehicle to cross it. It may also be employed as a floating pontoon for use as a ferry, or as part of a temporary pontoon bridge, or as a floating support for the superstructure of temporary bridges, particularly in a non-navigable river.

Other features and advantages of the invention will be better understood from perusal of the following description of one embodiment thereof and from reference to the accompanying drawings of said embodiment and in which:

FIG. 1 is an elevational view of a semi-rigid spanning member according to the invention,

FIG. 2 is a plan view of the member of FIG. 1,

FIG. 3 is a cross-sectional view along line III-Ill of FIG. 1,

FIG. 4 is a cross-sectional view along line [VIV of FIG. 2,

FIG. 5 is a cross-sectional view along line VV of FIG. 2,

FIG. 6 is a cross-sectional view along line VIVI of FIG. 2,

FIG. 7 is an elevation view showing a method of using the spanning members to support a bridge superstructure and FIG. 8 is a partial cross-sectional view of the method of connecting the plates together.

Referring now to the drawings, in FIGS. 1, 2 and 3 there is shown a semirigid spanning member according to the invention which is made up of a plurality of inflatable members 1 arranged inside an envelope 2, above which are arranged rigid plates 3 which are connected together end to end and which form an arched bearing surface. The inflatable members 1 and the envelope 2 are produced in a known way and are made from an elastomer-coated fabric. The envelope 2 is bordered by a cable 4 which is engaged in channels 5 provided on either side of plates 3. At various points along the top of the channel 5 are provided cut-outs 6 in which are engaged checks 7 which bear a rod 8 onto which is screwed a clamping nut 9 which bears against the channel 5. When checks 7 are engaged in channel 5 they lock in position the cable 4 which is resting against an edge 10 of channel 5.

At each end of the spanning member is provided a heel-plate ll, 11a which is shown in cross-section in FIG. 4 Each heel-plate ll, Ila contains a seating 12 into which fits the last of the plates 3.

A clamping plate I7 holds the ends 18 of parts 1 and 19 of the envelope 2 in position against the heel-plate ll, envelope 2 being provided with a cable 20 and the said plate l7 being fixed to the heel-plate by screws I3 and I4 which have nuts I5 and 16.

As shown in FIG. 6, rigid plates 3, 3a have adjoining edgings 27, 27a which on the one hand are provided at the bottom with hinge members 28, 280 which enable the plates to be joined together edge to edge by means of a pin 29, and on the other hand are provided at the top with bearing noses 21, 210 which allow the plates to butt against one another under load.

To ensure that the span will remain rigid even if one of the inflatable members 1 providing support should be damaged, uninflated reserve chambers 40 are provided inside the envelope and these can be inflated if required. The reserve chambers 40 may be separate chambers within the members 1 or they may be formed by securing a web 41 across the interior of each such member 1, so that within each member 1 there are two separately inflatable chambers. The reserve chamber, in either case, is formed of unreinforced, thin, flexible elastic plastic material. Thus, if the primary chambers suffer local damage, the reserve chambers may be inflated to adapt to the internal shape of the walls of the primary chambers, as defined by their inflated condition.

In FIGS. 1, 2 and 3 is shown a method of using the semi-rigid spanning member according to the invention to allow a vehicle 22 to cross a gap or opening in open terrain.

Because the spanning members are provided with inflatable members, they may be used as lighters 23, 23a

3 (FIG. 7) the bearing surface 24, 24a of which takes a pillar 25, 25a on which are mounted parts 26,=26a, 26b of the superstructure of a temporary bridge. 14

in FIG. 8 are shown two rigid plates 3, 3a which are formed by a section 30 made from honeycomb material which is arranged between two thin plates 31, 31a.

At adjoining edges, the plates 3, 3a have profiled members 32, 32a which form brackets and the flanges of which contain a series of holes 33, 33a in which fit a series of pins such as 34 which thus allow the plates to be joined together edge to edge.

It was envisaged above that uninflated reserve chambers which could be inflated in the event of one of the inflated members being damaged might be used.

However, in accordance with another embodiment, the uninflated reserve chambers which are made from unreinforced sheets of very thin, flexible and elastic plastics material, are housed inside the limitedexpansion chambers made from coated fabric which are used under normal conditions, so that if the second chambers should suffer local damage, a seal may be reestablished by inflating the first chambers, which then form an impermeable film by adapting to the internal shape of the walls of the second chambers.

Various modifications may, of course, be made by the man skilled in the art to the arrangements or methods which have just been described merely as nonlimiting examples, without exceeding the scope of the invention as defined by the appended claims.

I claim:

1. In a semi-rigid inflatable spanning member constituted by a plurality of inflatable members housed within an envelope above which are arranged rigid plates which are connected together end to end and which form an arched bearing surface, said envelope being bordered by a cable having ends engaged in lateral channels provided on either side of said rigid plates, and locking means holding said cable in place in the said channel.

2. An inflatable spanning member according to claim 1 wherein a heel-plate is provided at each end of said spanning member, into which heel-plate fits the last of said plates and against which heel-plate the ends of said inflatable members and of said envelope, are held in position by a clamping plate, said envelope being provided with an end retaining cable.

3. An inflatable spanning member according to claim 2, wherein the ends of each of said inflatable members and of said envelope are apertured to receive screws for clamping said clamping plate against said heelplate.

4. An inflatable spanning member according to claim I, wherein said rigid plates have adjoining edgings which are provided at the bottom thereof with hinge members which enable the plates to be joined together edge to edge by means of a pin, and at the top thereof with bearing noses which allow the plates to butt together under load.

5. An inflatable spanning member according to claim 1, wherein at least one pillar is supported by the bearing surface of said member and bridge superstructure is supported on said pillar.

6. An inflatable spanning member according to claim 1, wherein uninflated reserve chambers which can be inflated in the event of one of said inflatable members being damaged are also arranged within said envelope.

7. A semi-rigid inflatable spanning member according to claim 1, wherein said rigid plates are constituted by a section made of honeycomb material arranged between two thin plates the adjoining edgings of which are provided with profiled members forming apertured brackets into which apertures fit a series of pins for joining said plates together edge to edge.

8. An inflatable spanning member according to claim 6, wherein said uninflated reserve chambers are made from unreinforced sheets of very thin flexible and elastic plastic material, and are accommodated within said inflatable chambers made of coated fabric which are used in nonnal operation, so that, if said inflatable chambers should suffer local damage, a seal may be reestablished by inflating said reserve chambers which then form an impermeable film by adapting to the internal shape when inflated of the walls of said inflatable chambers. 

1. In a semi-rigid inflatable spanning member constituted by a plurality of inflatable members housed within an envelope above which are arranged rigid plates which are connected together end to end and which form an arched bearing surface, said envelope being bordered by a cable having ends engaged in lateral channels provided on either side of said rigid plates, and locking means holding said cable in place in the said channel.
 2. An inflatable spanning member according to claim 1 wherein a heel-plate is provided at each end of said spanning member, into which heel-plate fits the last of said plates and against which heel-plate the ends of said inflatable members and of said envelope, are held in position by a clamping plate, said envelope being provided with an end retaining cable.
 3. An inflatable spanning member according to claim 2, wherein the ends of each of said inflatable members and of said envelope are apertured to receive screws for clamping said clamping plate against said heel-plate.
 4. An inflatable spanning member according to claim 1, wherein said rigid plates have adjoining edgings which are provided at the bottom thereof with hinge members which enable the plates to be joined together edge to edge by means of a pin, and at the top thereof with bearing noses which allow the plates to butt together under load.
 5. An inflatable spanning member according to claim 1, wherein at least one pillar is supported by the bearing surface of said member and bridge superstructure is supported on said pillar.
 6. An inflatable spanning member according to claim 1, wherein uninflated reserve chambers which can be inflated in the event of one of said inflatable members being damaged are also arranged within said envelope.
 7. A semi-rigid inflatable spanning member according to claim 1, wherein said rigid plates are constituted by a section made of honeycomb material arranged between two thin plates the adjoining edgings of which are provided with profiled members forming apertured brackets into which apertures fit a series of pins for joining said plates together edge to edge.
 8. An inflatable spanning member according to claim 6, wherein said uninflated reserve chambers are made from unreinforced sheets of very thin flexible and elastic plastic material, and are accommodated within said inflatable chambers made of coated fabric which are used in normal operation, so that, if said inflatable cHambers should suffer local damage, a seal may be re-established by inflating said reserve chambers which then form an impermeable film by adapting to the internal shape when inflated of the walls of said inflatable chambers. 